U.S. patent number 7,118,551 [Application Number 09/470,009] was granted by the patent office on 2006-10-10 for non-metal reinforcing mandrel.
This patent grant is currently assigned to Advanced Cardiovascular Systems, Inc.. Invention is credited to Jeong S. Lee, Ken Wantink.
United States Patent |
7,118,551 |
Lee , et al. |
October 10, 2006 |
Non-metal reinforcing mandrel
Abstract
An apparatus for providing support along the length of a
catheter is described. The present invention consists of a mandrel
fabricated from a non-metal. The mandrel extends through the lumen
of a dilatation catheter to provide added support and stiffness to
the catheter shaft. The stiffness along the length of the non-metal
mandrel may easily be varied by making dimensional or morphological
changes to the polymeric mandrel.
Inventors: |
Lee; Jeong S. (Diamond Bar,
CA), Wantink; Ken (Temecula, CA) |
Assignee: |
Advanced Cardiovascular Systems,
Inc. (Santa Clara, CA)
|
Family
ID: |
37072368 |
Appl.
No.: |
09/470,009 |
Filed: |
December 22, 1999 |
Current U.S.
Class: |
604/96.01 |
Current CPC
Class: |
A61M
25/104 (20130101); A61M 2025/0063 (20130101) |
Current International
Class: |
A61M
29/00 (20060101) |
Field of
Search: |
;604/164.01,164.13,264,96.01,93.01,95.03,164.1,164.11,528,523,524,525 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0277368 |
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Dec 1987 |
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EP |
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0515119 |
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May 1992 |
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EP |
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WO 90/08567 |
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Jan 1990 |
|
WO |
|
WO 93/18813 |
|
Mar 1993 |
|
WO |
|
95/16862 |
|
Dec 1995 |
|
WO |
|
Primary Examiner: Lucchesi; Nicholas D.
Assistant Examiner: Koharski; Christopher D.
Attorney, Agent or Firm: Fulwider Patton LLP
Claims
What is claimed is:
1. A catheter comprising: an elongated catheter shaft having an
inner tubular member with a lumen, and an outer tubular member
disposed about the inner tubular member such that a lumen of the
outer tubular member is defined therebetween; and a variable
stiffness mandrel disposed in said outer tubular member lumen,
having a solid core comprised of a non-metal material, a bonded
proximal end section which fixedly secures the mandrel relative to
the catheter shaft, an annealed proximal section which is located
between and spaced apart from an outer surface of the inner tubular
member and an inner surface of the outer tubular member and which
has a first crystallinity, and a non-annealed distal section with a
second crystallinity lower than said proximal section first
crystallinity such that the proximal section is stiffer than the
distal section.
2. The catheter of claim 1 wherein said material is selected from
the group consisting of polyamides, polyetheretherketone,
polyphenylene sulfide, polyetheramide, polyimide, and any
combination thereof.
3. The catheter of claim 1 wherein said proximal section is larger
than a diameter of said distal section of said mandrel.
4. The catheter of claim 1 further comprising an inflatable member
secured to the catheter shaft, wherein said distal section of said
mandrel extends to a location along the length of the catheter
located in the inflatable member.
5. The catheter of claim 1 further comprising an inflatable member
secured to the catheter shaft, and wherein the distal section of
the mandrel extends to a location proximal to the inflatable
member.
6. The catheter of claim 1 wherein said mandrel is formed by
necking at high temperatures such that said proximal section is
stiffer than said distal section.
7. The catheter of claim 1 wherein said mandrel is formed by taper
extruding such that said proximal section is stiffer than said
distal section.
8. A catheter comprising: an outer member; a hollow inner member
extending through said outer member; an outer lumen between said
inner and outer members; and a non-metal mandrel formed of a
polyetheretherketone polymeric material, extending through said
outer lumen, said mandrel having an annealed proximal section
located between and spaced apart from an outer surface of the inner
member and an inner surface of the outer member having a first
crystallinity, and a non-annealed distal section having a second
crystallinity lower than the proximal section first crystallinity,
and being uniformly tapered from the proximal section to the distal
section.
9. The catheter of claim 8 wherein a diameter of said proximal
section is larger than a diameter of said distal section of said
uniformly tapered mandrel.
10. The catheter of claim 8 further comprising an inflatable member
having an inflatable interior, and comprising a proximal portion
secured to a distal portion of the outer member and a distal
portion secured to a distal portion of the inner member, wherein
said distal section of said mandrel extends to a location along the
length of the catheter located in the inflatable member.
11. The catheter of claim 8 further including an inflatable member
secured to the outer member and the hollow inner member with an
interior in fluid communication with the outer lumen and wherein
the distal section of the mandrel extends to a location proximal to
the inflatable member.
12. The catheter of claim 8 wherein said mandrel is formed by
necking at high temperatures such that said proximal section is
stiffer than said distal section.
13. The catheter of claim 8 wherein said mandrel is formed by taper
extruding such that said proximal section is stiffer than said
distal section.
14. The catheter of claim 8, wherein said mandrel is fixed to lock
said mandrel in place relative to said catheter outer member.
15. The catheter of claim 8 wherein said hollow inner member
defines a guidewire receiving lumen.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to catheters. More
particularly, the present invention relates to a non-metal
reinforcing mandrel for use with such catheters.
2. Description of Related Art
In percutaneous transluminal coronary angioplasty (PTCA), catheters
are inserted into the cardiovascular system via the femoral artery
under local anesthesia. A pre-shaped guiding catheter is positioned
in the coronary artery, and a dilatation catheter having a
distensible balloon portion is advanced through the guiding
catheter into the branches of the coronary artery until the balloon
portion traverses or crosses a stenotic lesion. The balloon portion
is then inflated with a fluid to compress the atherosclerosis in a
direction generally perpendicular to the wall of the artery,
thereby dilating the lumen of the artery. After the last dilation,
the balloon is deflated so that the dilatation catheter can be
removed from the dilated stenosis and blood flow can resume through
the dilated artery.
Ongoing development work of the dilatation catheters has reduced
the transverse dimensions of the catheters for angioplasty
procedures both as to their outer diameters as well as to the wall
thickness of the catheter's tubular components. This reduction has
led to difficulties in designing dilatation catheters having small
transverse dimensions while still maintaining adequate pushability
for advancement of the dilatation catheter through the guiding
catheter into the patient's coronary artery and across tight
stenoses. The marginal or inadequate pushability has been
particularly noticeable with over-the-wire catheters that have been
adapted for use with guidewires having diameters not more than
about 0.014 inch (0.356 mm).
One solution to this dilemma has been the use of a reinforcing
mandrel 24, such as the one shown in FIGS. 1A and 1B. The catheter
10 typically has an inner tubular member 12 with an inner lumen 14
adapted to receive a guidewire with a maximum OD of less than about
0.014 inch. An outer tubular member 16 is generally disposed about
the inner tubular member 12 such that the inner tubular member 12
extends through the outer tubular member 16 and an outer lumen 18
is defined therebetween. The inflatable member (e.g., a balloon) 20
has a proximal end 21 which is secured to the distal end of the
outer tubular member 16 and a distal end 23 secured to the distal
end of the inner tubular member 12 so as to seal off the outer
lumen 18 and the interior of the inflatable member 20.
The reinforcing mandrel 24 is within the outer lumen 18 between the
inner 12 and outer 16 tubular members and extends from the proximal
end of the catheter 10 into the distal portion of the catheter 10
but typically ends short of the inflatable member 20. The mandrel
24 is usually a cylindrical, often tapered axle inserted onto a
device such as a catheter 10 to provide support along the length of
the given device. The mandrel 24 is typically secured at the
proximal end of the mandrel 24 within the adapter (not shown)
mounted at the proximal end of the catheter 10.
Although difficult to achieve during processing, it is often
desirable to vary the diameter of the mandrel 24 to establish a
predetermined amount of flexibility. For example, since it is
generally desirable for the proximal section of the catheter 10 to
be more stiff to assist in the catheter's pushability, the proximal
section of the mandrel 24 is designed/fabricated to have a larger
diameter than the diameter of the mandrel 24 in a more distal
section of the catheter 10. The smaller diameter portion of the
mandrel 24 extending into the distal section of the catheter shaft
10 preferably has a transverse dimension of at least 20% less than
the transverse dimension of the proximal section of the mandrel 24.
This variation in the diameter of the mandrel 24 provides
flexibility in the distal portion of the catheter 10 and allows the
catheter 10 to track over the guidewire while still maintaining
excellent pushability.
The mandrel 24 of the prior art is fabricated from a metal or metal
alloy (hereinafter metal) rod. The metal mandrels 24 known in the
prior art, however, have several inherent limitations. First, metal
rods are generally too stiff for angioplasty procedures, and a too
stiff rod reduces a catheter's trackability over a guidewire or
other medical device. Not only is the rod often too stiff, but a
metal rod is also more difficult to process. For example, the metal
rod must be ground to the desired diameter for the various (i.e.,
proximal and/or distal) section and often still retains sharp edges
along its length that can damage the interior of the catheter
shaft. Further, the dimensions of a metal mandrel are fixed during
fabrication.
It would be advantageous to replace the metal mandrels of the prior
art with a non-metal mandrel that has more easily varied dimensions
and stiffness characteristics along the length of the mandrel. The
ability to easily vary the dimensions and stiffness characteristics
of a mandrel will also allow more freedom in the choice of
materials for the catheter shaft itself. In other words, because
the stiffness of the mandrel can be easily varied during
processing, the proximal section of the mandrel can be made stiff
enough to provide the desired pushability for the catheter. A
mandrel having a stiff proximal section reduces the need for a
stiff proximal section of the catheter shaft itself. Thus, the
material for the proximal shaft of the catheter will no longer be
limited to a stiff polymer. By allowing the use of a less stiff
polymer in the proximal section, the non-metal mandrel will also
substantially reduce the likelihood of kinking. In this manner, a
mandrel having a stiffer proximal section will provide the desired
pushability without having to sacrifice the flexibility of the
distal shaft of the catheter.
SUMMARY OF THE INVENTION
An apparatus for providing support along the length of a catheter
is described. The present invention consists of a mandrel
fabricated from a non-metal. The mandrel may extend through the
outer lumen of a dilatation catheter to provide added support and
stiffness to the catheter shaft. The stiffness along the length of
the non-metal mandrel may easily be varied by making dimensional or
morphological changes to the polymeric mandrel.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is further described by way example with reference to
the accompanying drawings, wherein:
FIG. 1A is a side cross-sectional view of a mandrel of a first
embodiment of the present invention as used with a dilation
catheter.
FIG. 1B is a front cross-sectional view of the mandrel and catheter
illustrated in FIG. 1A.
DETAILED DESCRIPTION OF THE INVENTION
An apparatus for providing support for a catheter is described. In
the following detailed description, numerous specific details are
set forth in order to provide a more thorough understanding of the
present invention. However, it will be appreciated that the present
invention may be practiced without these specific details. In other
instances, well-known devices, methods, procedures, materials, and
individual components have not been described in detail so as not
to unnecessarily obscure aspects of the present invention.
A mandrel is usually a cylindrical, often tapered, axle/rod
inserted into a device such as a catheter to provide support along
the length of the device. In the prior art, mandrels used with
biomedical devices have been fabricated from a metal or metal alloy
(hereinafter metal). The metal mandrels, however, have been
encumbered by several limitations including difficulty in
processing mandrels having a desired varying diameter, sharp edges
that may damage the device the mandrel is inserted into, and an
often excessive stiffness. The present invention addresses each of
the above issues by providing a non-metal mandrel.
FIGS. 1A and 1B are illustrations of a reinforcing mandrel 24 used
with a dilatation catheter 10. The catheter 10 has an inner tubular
member 12 with an inner lumen 14 adapted to receive a guidewire
(not shown). An outer tubular member 16 is generally disposed about
the inner tubular member 12 such that the inner tubular member 12
extends through the outer tubular member 16 and an outer lumen 18
is defined therebetween. The inflatable member (e.g., a balloon) 20
has a proximal end 21 that is secured to the distal end of the
outer tubular member 16, and a distal end 23 that is secured to the
distal end of the inner tubular member 12 so as to seal off the
outer lumen 18 and the interior of the inflatable member 20.
The reinforcing mandrel 24 is typically within the outer lumen 18
between the inner 12 and the outer 16 tubular members and extends
from the proximal end of the catheter 10 into the distal
portion/section of the catheter 10. The mandrel 24 typically ends
short of the inflatable member 20.
The mandrel of the present invention is fabricated from a non-metal
material. The material for the non-metal mandrel may be selected
from numerous materials including, but not limited to: nylons,
including high stiffness polyamides; stiff polymers with tensile
modules greater than approximately 400,000 psi, such as PEEK
(polyether etherketone), PPS (polyphenylene sulfide), PEI
(polyetheramide), and PI (polyimide); liquid crystalline polymers;
polymers reinforced with glass fibers; polymers reinforced with
graphite fibers, etc.
By fabricating the mandrel of a catheter from a non-metal material,
the present invention provides numerous advantages over the prior
art. Without the use of a mandrel, the proximal section of a
catheter shaft must generally be made of a stiff polymer in order
to provide a sufficient amount of pushability. However, a stiff
polymer shaft kinks easily during manipulation of the catheter into
the desired position with the cardiovascular system of the patient.
The metal mandrel of the prior art provides stiffness for the
catheter in addition to the catheter shaft itself. However, the
flexibility of a metal mandrel is difficult to vary, often
resulting in a too stiff mandrel which makes the steering of the
catheter much more difficult. The stiffness of the non-metal
mandrel of the present invention may be varied as needed along the
length of the mandrel as requested by the desired stiffness
characteristics of a given section of the mandrel. For example, it
is generally desirable for the proximal section of the catheter to
be more stiff than the distal section of the catheter and thus the
same is true for the mandrel.
Whereas with the prior art metal mandrel, grounding is one of the
few means for tapering the diameter (i.e., having a diameter that
gets smaller as the length of the mandrel is traversed from the
proximal end to the distal end) and achieving a varying stiffness
(the larger the diameter the more stiff the mandrel), non-metal
mandrels may have dimensional and morphological changes achieved in
a variety of ways. For example, the diameter of a non-metal mandrel
may be tapered from the proximal end to the distal end, by a taper
extruding, or by necking the mandrel at high temperatures during
the initial fabrication of the mandrel. Sometimes, annealing the
proximal portion of the mandrel induces a higher crystallinity
which also makes the annealed proximal portion of the mandrel more
stiff than the non-annealed distal portion of the mandrel.
By providing means for supporting a catheter shaft such that the
stiffness of the support maybe varied as needed, the non-metal
mandrel of the present invention also eliminates the previous
limitation requiring the catheter shaft to be made of a stiff
polymer in order to provide the desired pushability. Further, the
non-metal mandrel of the present invention is fabricated from a
material that is more compatible with the standard materials used
for the catheter shaft. This compatibility between the mandrel and
the catheter shaft allows the mandrel to be able to be fused to the
shaft by heating if desired. The fusion process locks the mandrel
in place and makes the external force and support to be applied
more efficiently.
Thus, the non-metal mandrel of the present invention provides
numerous advantages over the prior art metal mandrel. The non-metal
mandrel allows for both dimensional and morphological changes that
may be varied to control the stiffness characteristics of both the
mandrel and the catheter shaft or sheath the mandrel is inserted
into. The capability of varying the stiffness of the mandrel along
its length allows the mandrel to provide the greater desired
pushability without sacrificing the needed flexibility in the
distal shaft. This also reduces the need for stiff polymer catheter
shafts, which greatly reduces the chance of kinking along the
catheter shaft.
* * * * *